LMS Campus Manager VLAN to Subnet mapping

Answered Question
Mar 17th, 2010

Hello,

I am having some problems with the UserTracker in Campus Manager 5.2.1 under LMS 3.2 not discovering the Subnet, IP address, and Hostname for some devices. Also, under the User Acquisition settings I am  missing a large number of subnets on the network.

Looking at the discovery process (as per Cisco documentation),

Step 1. Discover the Devices
Step 2. Read the VTP Domain
Step 3. Read the VLANs
Step 4. Read the MAC Addresses
Step 5. Map VLANs to Subnets
Step 6. Perform Ping Sweeps
Step 7. Resolve IP Addresses
Step 8. Resolve Host Names
Step 9. Resolve Phone Extensions
Step 10. Discover User Names

it seems that step 5 is where it fails on some routers. All the devices with missing information are on VLANs that are routed through 6500's, 4500's, and a FWSM inside a 6500. Devices connected through 3750's are fine.

I found in a Cisco document that:

"The discovery creates groups of interfaces that  are connected to the same link or segment in the database. ANI looks at all  the CDP neighbors on a router interface until it finds a neighboring interface  that is a port on a switch. The discovery reads the IP address and subnet mask  on the router interface to learn the subnet. It reads the VLAN on the switch  port to learn the VLAN."

This would explain why it doesn't work on the FWSM because it doesn't support CDP. Is this correct?

But what about the 4500's and 6500's? Is there some configuration that needs to be changed?

Thank you.

I have this problem too.
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Correct Answer by Joe Clarke about 6 years 8 months ago

What is acting as a router for these subnets?  If it is an FWSM, then you will not be able to get IP, Subnet, or hostname information in UT because the FWSM is not supported by Campus Manager.

Stated another way, UT will query the ARP tables of the routers on each subnet via SNMP.  It then uses those ARP entries to populate the IP and Subnet fields in the end hosts report.  From the IP, it will do a lookup in DNS/hosts file to get the end host hostname.  If the routers containing the ARP entries are not Data Collected by Campus (e.g. if the router isn't supported by Campus), then UT will not learn the required ARP information.

Cat4500 and 6500 switches which are acting like routers (i.e. have IP routing enabled) will have their ARP tables queried by UT.  As long as they are properly Data Collected, and have the ARP entries for the end hosts, they should be able to provide that information to UT.

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Correct Answer
Joe Clarke Fri, 03/19/2010 - 10:26

What is acting as a router for these subnets?  If it is an FWSM, then you will not be able to get IP, Subnet, or hostname information in UT because the FWSM is not supported by Campus Manager.

Stated another way, UT will query the ARP tables of the routers on each subnet via SNMP.  It then uses those ARP entries to populate the IP and Subnet fields in the end hosts report.  From the IP, it will do a lookup in DNS/hosts file to get the end host hostname.  If the routers containing the ARP entries are not Data Collected by Campus (e.g. if the router isn't supported by Campus), then UT will not learn the required ARP information.

Cat4500 and 6500 switches which are acting like routers (i.e. have IP routing enabled) will have their ARP tables queried by UT.  As long as they are properly Data Collected, and have the ARP entries for the end hosts, they should be able to provide that information to UT.

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